Current door and window sensors operate in a binary mode: open or closed indicators. In particular, door and window sensors that rely on a magnetic switch can be defeated by securing a magnet in a correct position to falsely hold a reed switch in a closed position. These sensors have limited capability in the adjustment of the magnet placement. The dynamic range between the magnet and the sensor is principally for compensation of the gap between the magnet and the sensor due to the door/window construction and is restricted to fairly narrow separations.
The typical security sensor uses a reed switch that is placed in very close proximity (usually less than 1″) to a magnet to indicate only an open or closed state. So, if a homeowner wants to sleep with his or her window cracked ajar, the homeowner would need to either disarm the security system completely or install two magnets (one for the open position, and one for the closed position) and very carefully open the window to a specific position to avoid triggering an open state with an alarm system.